Methods of using treatment fluids and, more particularly, methods of using treatment fluids comprising calcium aluminate cement compositions in well operations are provided.
Cement compositions may be used in a variety of subterranean operations including operations that utilize treatment fluids. A broad variety of cement compositions have been used as treatment fluids. In some instances, extended-life cement compositions have been used. In contrast to conventional cement compositions that set and harden upon preparation, extended-life cement compositions are characterized by being capable of remaining in a pumpable fluid state for at least about one day (e.g., about 7 days, about 2 weeks, about 2 years or more) at room temperature (e.g., about 80° F.) in storage. When desired for use, the extended-life cement compositions should be capable of activation and consequently develop reasonable compressive strengths. For example, an extended-life cement composition that is activated may set into a hardened mass. Among other things, extended-life cement compositions may be suitable for use in treatment fluids where it is desirable to prepare the treatment fluid in advance. This may allow the treatment fluid to be stored prior to use. In addition, this may allow the treatment fluid to be prepared at a convenient location before transportation to the job site. Accordingly, capital expenditures may be reduced due to a reduction in the need for on-site bulk storage and mixing equipment. This may be particularly useful for offshore operations where space onboard the vessels may be limited.
Drilling and fluid displacement are two subterranean operations that utilize treatment fluids. Drilling requires the use of drilling fluid or as it is also known, drilling mud. Drilling fluids may be used to maintain hydrostatic pressure in the wellbore, prevent formation damage, suspend cuttings, and to transport cuttings to the surface. Drilling fluids may be water-based or oil-based. Typical water-based drilling fluids may be composed of solely water or a mixture of water and various types of clay. Oil based drilling fluids typically use a base fluid of a petroleum product.
Fluid displacement utilizes one or more fluids to displace another fluid from the wellbore. Typically this may be done to prevent contamination of one fluid with another or the contamination of one fluid with the formation. A displacement fluid or as it is also known, a spacer fluid, may be water-based fluids. In most instances, spacer fluids may be used to separate drilling fluid from a cement composition during a cementing operation. Because the spacer fluid will be used to separate two other fluids, such as the drilling fluid and the cement composition, the spacer fluid should be compatible with both treatment fluids.
Spotting fluids may be used to remove drilling fluid and prevent the drilling fluid filter cake from interfering with subsequent primary cementing operations, this may be a potential problem where differential sticking stops a drill pipe. A spotting fluid may be used to at least partially displacing the drilling fluid before the drilling fluid in the wellbore has had a chance to gain significant gel strength, for example, prior to introducing the pipe string into the well bore. Generally, these spotting fluids should not have an undesirable increase in gel strength after being static in the wellbore for a period of time, for example, up to at least two weeks, so that the spotting fluids may be displaced from the wellbore. After the wellbore is at least partially filled with a spotting fluid, the pipe string to be cemented may be introduced into the wellbore. When the cement composition is pumped through the pipe string into the annulus, the drilling fluid (if any) and the spotting fluid in the pipe string and annulus may be displaced ahead of the cement composition.
Switching between treatment fluids in a subterranean operation can be costly in both time and resources. Varied fluid types may require separate fluid storage, additional manpower, and additional equipment. In addition to the increased operating expenses, varied fluid use may create additional worksite problems such as higher environmental burdens, fluid incompatibilities, and the inability to reuse fluids and materials once their respective portion of the operation has been completed.